The overall aim of this project is to learn more about mechanisms involved in the induction of bladder cancer in rats with known bladder carcinogens. Primary emphasis will be given to the study of the metabolism N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) and its principal urinary metabolite, N-butyl-N-(3-carboxypropyl)nitrosamide (BCPN) Comparative studies will be carried out with other nitrosamines or nitrosamides, such as N-methyl-N-(3-carboxypropyl)nitrosamine (MCPN) and N-methyl-N-nitrosourea (MNU).